What Could be Done Further?

These are just random "brainstorming" type ideas I've had that might improve things further at considerably less cost.  After dropping a huge chunk of change on what we just did, I'm not inclined to rush out and spend more money.  I'll probably spend at least one winter just with this, just to see what the net effects are.  But if anyone has any suggestions, please contact me at:

1. Fix leaks.  While we're pretty sure the total insulation is good, there may be "cold spots" in the attic or along the edges where the walls meet the ceiling of the house, or around the edges of the doors and windows, where heat could leak through.  We could get this tested by having some insulation company come out and test for cold spots using an infrared detection device.

2. Increase the R-value in the attic.  We had previously brought the attic up to R-50.  For another $1000, we could probably increase this to R-100.  No idea whether this would do any good.  We originally added the attic insulation in the summer of 2006, and in the winter of 2006-7 did not notice any appreciable decrease in heating requirement, but that may have been because the rest of the house was so badly insulated.

3. Insulate the interior of the basement walls maybe up to R-10 or R-15.  I'm not sure what this would set us back (another $10,000?), but it might enable us to survive the winter in the basement with no heat at all.

4. Add storm windows.  Since we missed our opportunity to get R-9 windows, maybe this would help the main deficiency in insulation right now.  Of course with unlimited money, we'd just replace the windows with the new R-9 type windows, but I'm thinking that storm windows might do just as good a job. 

5. (Feb. 2, 2009) Correct thermal bridging problem with doorsteps.  There is some thermal bridging in the thicker walls themselves, because the wood framing intersects at certain points.  But there's another possibility, and that is that the doorsteps and back porch constitute an opportunity for bridging as well.  The doorsteps are poured concrete directly attached to the concrete block / brick mass.  Wood has an R-value of 1.25 per inch, but poured concrete has an R-value of 0.08.  This may be the single best opportunity to improve the insulation.  I don't know exactly what materials to use instead of concrete, though.  

6. (Feb. 2, 2009) Is the air exchanger oversized?  Perhaps too much fresh air is cycling into the house.  Thanks to "lengould" of TheOilDrum.com for making this suggestion.